The present invention relates to an auxiliary brake employed when a main brake system for an automobile operates, and more particularly, to an auxiliary brake which operates smoothly even when a high brake operating pressure is applied thereto.
Generally, an auxiliary brake is called an ABS brake. Related techniques are disclosed in Korean Patent No. 1992-10515, U.S. Pat. Nos. 343,066, 4,571,007 and 5,161,864. The applicant filed Korean Utility Model No. 15568. These apparatuses are designed to maintain the pressure balance of operation oil applied to a brake system in operating a main brake.
They usually have a housing that oil enters, including a resilient rubber and operating gas for maintaining the pressure balance of oil.
Those apparatuses are constructed with a plate-shaped resilient rubber interposed in an oil operating space, or with a resilient rubber that defines a space for receiving operating oil. In either construction, the surface area of the rubber subjected to the operating oil remains constant regardless of the operating pressure of the oil. For this reason, there is a limit in coping with the pressure variation of brake operating oil. Specifically, according to the pressure variation of brake operating oil, the resilient rubber should work elastically in order to accomplish the pressure balance of oil. However, the resilience action of the rubber reaches its limit when the operating oil pressure is high above a predetermined level. As a result, the resilient rubber does not function properly at high operating pressures.